He added that cranial injuries have been identified in a number of ceratopsians like Triceratops. These dinosaurs are known for their stocky bodies, head horns, beaks and fondness for plants.
It is likely that these dinosaurs also fought with their heads, possibly locking horns as some horned and hoofed animals do today.
Other animals therefore might have regularly heard the sounds of dinosaur heads bashing into each other during the Jurassic and Cretaceous Eras.
"While no other animal has a head built like pachycephalosaur, cranial ornamentation ... is not all that rare in nature," he said.
Andrew Farke, curator of paleontology at the Raymond M Alf Museum of Paleontology in California, told Discovery News, "Based on all of the evidence, I think it is likely that pachycephalosaurs butted their heads against 'something' -- probably each other. Everything, including the new work from Peterson and colleagues, is consistent with this idea."
Farke continued, "Certainly, not all dinosaurs butted heads -- some have skulls better suited to this than others. But, for the thick-headed pachycephalosaurs, there is little doubt in my mind that they were ramming their skulls."